Fuel pump injector



Jan. 24, 1939. c. w. TRUXELL, JR 2,144,862

FUEL PUMP INJECTOR Filed April 3. 1937 Patented Jan.z4, 1939 PATENT OFFICE FUEL PUMP AINJECTOR.

Clyde W. Truxell, Jr., Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April s, 193i-,l serial No. 134.767

4 Claims.

This invention relates to liquid fuel injectors for internal combustion engines.

More particularly it is concerned with injectors having a pump and nozzle combined in one unit 5 and specifically it relats to improvements in the structure shown Vin U. S. Patent No. 1,981,913 of November 27, 1934.

In such unit fuel pump injectors having plunger controlled ports in the cylinder wall communicating with an annular fuel reservoir external of the cylinder, it has been usual to make the cylinder as a bushing separate from the pump body, and to seal this bushing by press fits and the like within the body in such a way as to leave a space between the cylinder bushing and the pump body, Y to constitute the annular reservoir. The injection valve is commonly of the needle valve type involving cylindrical lapped surfaces, and small drilled parts. I t has been difficult to secure adequate strength in these parts to withstand the high pressures to which they are subjected, with a minimum leakage and with a minimum volume of fuel under compression.

'I'he object of the present invention is an improved design of fuel pump and injector which will b`e simpler and cheaper to make.

A further object of the invention is a construction in which the need for cooperating clamping shoulders on the pump cylinder and the pump body is eliminated, to permit of a heavier,

stronger design within the same over-all dimensions.

A-f still further object of the invention is an improved construction of injection valve and fuel pump combined, in which the volume of fuel under compression is reducedpto a minimum.

The above and other objects of the invention will be apparent as the description proceeds. According to the invention the pump cylinder is preferably an integral part of the pump body and the annular reservoir therearound is provided by a sleeved nut, through which the injection valve housing the spray nozzle and any other necessary stationary pieces arranged axially of the pump .cylinder and at the delivery end thereof are held in abutting and tightly sealed relationship to the end of the pump cylinder, and the pump block.

The injection valve is of the spring loaded disc Fig. 2 is an enlarged view of a part of Fig. 1.

Fig. 3 is a persepctive view of the disc valve of Fig. 2.

The pump' plunger I, has at its lower end, an annular groove or space 2, dividing the circum- 5 ferential surface of the plunger into two parts. 'I'he lower surface is bounded by the bottom cir- Y cumferential edge I and a helical edge 3, while the upper surface has a helical edge 4. A channel or duct 5 connects the annular space between the l0 edges 9 and I with the pumping space 6 below the end of the plunger.

'I'he plunger works in a cylinder 1 which is an integral part of the pump block 8. Below the cylinder 'l is adistance piece 9 having a bore l0 15 therethrough from the pumping space 6 to the spray nozzle Il which is provided vwith a spring loaded disc valve I2 which is opened against the pressure of a spring I3 on the delivery stroke of the pump plunger. 20

'I'he cylinder I and the parts 9 and Il are held in assembled and tightly sealed relationship by a sleeved nut -member Il screwed to the cylinder 1 at a point I5 close to the junction of the cylinde I and the block 8. 25

The length of the sleeved nut member Il is such that a tight seal between the parts 1, 9 and ll can always be obtained with clearancebetween the nut I4 and the block 8.

The bore of the sleeved nut member Il is such 30 that an annular space constituting a fuel reservoir I9 is provided between the cylinder 'I and the nut member Il.

f Fuel oil from a suitable low pressure supply is supplied to the reservoir I6 through a pipe (not 35 shown) which is clamped between the washers I1 on a bored stud Il which is screwed into the block l. Within a counterbored pocket i9 in the stud i9, is a spring 29which holds an edge 'type filter 2l-on a shoulder 22 of a. pocket 23 in 4o the block 8, below the filter stud I8. 'Ihe fuel oil from the supply pipe passes through the stud Il, through the lter 2| and intothe pocket 23, whence it passes through drilled ducts 2l and 25 into the reservoir I6. Any or all of the parts just 45 described may be duplicated to provide a return line for the flow of surplus fuel oil from the reservoir back to the low pressure. source of Supply. v

The reservoir Il is sealed against leakage through the screw threaded joint I5, by means of a gasket ring 29 o! Copper orother suitable material pressed tightly incontact with the sleeve Il and the block I, by the wedge surface 21 of a nut 1l, screwed on the sleeved nut member I4. ly

' tially a two way Paxial' direction, 75l only'be, aoneway Suitable inlet and bypass ports 29 and 30 are provided between the pump cylinder and the annular reservoir I6, and the edges I', 3 and 4 on the plunger, constitute control edges therefor.

The arrangement of the ports and control edges in the cylinder and plunger is such that on the delivery stroke of the pump, after the closing of the inlet port 29 by the end I of the plunger, fuel is bypassed from the pump pressure space into the reservoir through the bypass port 30 until this port is covered by the edge 4 of the annular groove on the plunger; thereupon injection delivery of fuel begins and continues until the port 29 is uncovered by the edge 3 of the annular groove on the plunger.

The pump body 8 is counterbored at 3I to provide clearance around the plunger, and again at 32 to provide a pocket for a pinion 33. The plunger I has a at 34 milled on its side, to be engaged by asimilarflat in the bore of the pinion 33, so .that the plunger I may be turned by the pinion 33 but is capable of longitudinal reciprocating motion therein. The pinion 33 may be angularly turned by a rack 35 to adjust the position of the helical edges 3 and 4 in relation to the ports 29 and 30, to time the injection.

Above the pinion 33, the block 8 is again counterbored and threaded to receive a tubular guide 36 for the plunger follower 31.

The tubular guide 36 is screwed tightly on to a washer 38, which serves to retain the pinion 33 in its pocket 32.

The upper end of the plunger I is locked to the plunger follower 31 by a split locking plate 40 which engages an annular groove towards the end of the plunger and corresponding grooves in the side walls of the slotted end of the plunger follower 31. The connection permits the plunger I to be turned by the rack 35 and pinion 33 independently of the plunger follower, and the plunger alignment in its cylinder is independent of the alignment of the plunger follower.

From their position as shown in the drawing, the plunger follower 31 and the plunger I are moved downwardly on their delivery stroke by a. suitable cam 44, through the medium of a rocker arm 45 fulcrumed on a shaft V46 and provided with anti-friction rollers 41 and 48 at its ends.`

The return or suction stroke movement of the plunger is effected bythe spring 49, which exerts a force in opposition to the cam 44, and at all times tends to maintain the plunger'follower 31 in contact with the rocker arm 45, and the rocker arm 45 in contact with the cam 44.

The return spring 49 is a coilvspring in compression, disposed-externally of the tubular guide 36. It seats on a washer 5,0 on thepump block 8 and engages the outer end of the plunger follower 31 through 'the medium of aflanged seating collar 5I.'

.The seating collar 5I plunger follower 31, and is counterbored at 52y tol provide a vshoulder 53 which engages the underside or a spun making mate 54, which is retained in an annular groove 55 on the plunger follower by the walls of the counterbore 52.

The connecting joint between the plunger folthe connecting joint between the plunger follower and lock, sincev it prevents4 movement of the plunger relativelyto the follower in either -where the former is, and need lock, since'the spring thrust is a sliding `fit on the the plunger, except that the latter is essenon the flanged seating collar is always in the same direction.

Referring now particularly to Fig. 2, the spring I3 has a seating on the ange 60 of a stop and filler member 6I which rests in the bottom of a pocket 62 in the nozzle piece II. The member 6I is tubular and is castellated to provide four ducts 63.

The disc valve as 64.

When the pressure in duct III is suilicient to overcome the pressure of the spring I3, `the disc valve I2 is forced against the stop member 6I and the fuel oil can then pass from the duct I0 through the slots 64 in the disc valve I2, thence through the ducts 63 and the bore of the member I2 is provided with slots such 6I to the bore 65 of the nozzle piece II, and out through the spray holes 66.

The disc valve I2 has the advantage of sealing through a flat surface easily lapped, and it digests dirt better than a needle valve.

It will be seen also that the construction is such that there is only a minimum quantity of oil under compression.

The spray nozzle II projectsl through a hole 61 in the end of the sleeved nut member I4 which is lipped to provide a seating 68 for the spray nozzle II in the end of the sleeved nut, and through which theparts are clamped tightly together when the nut is tightened on its threads.

The outer periphery of the sleeved nut member I4 is provided with a shoulder 69 through which the whole injector assembly may be clamped on to a seating in an engine cylinder head such as 10.

The distance piece 9 and the spray nozzle II are a sliding fit in that part of the bore of the sleeved nut I4 in which they are located. The jointing surfaces of the cylinder 1, the distance piece 9 and the spray nozzle II are flat surfaces, easily lapped, to provide uid tight leak proof joints between the parts, when they are clamped together by the sleeved nut member I4.

I claim:

l. In a fuel pump injector, in combination, a pump cylinder, a spray nozzle, a distance .piece between the pump cylinder and the spray nozzle, a. fuel passage through the distance piece and the spray nozzle from the pump cylinder to the spray holes in the spray nozzle, a. counterbore in the 'i spray nozzle' constituting a. valve chamber, a disc valve therein having a fiat seating on the distance fthe flanged end of the stop and filler member and substantially 'the walls of the chamber filling the annular space between and the stop and filler member, and passageway means around the disc valve `and through the wall of the stop and filler member to provider for an unrestricted flow of fuel frorn the pump' cylinder tothe spray holes `v 1hen "the disc valve is offlts seating and in con- 1 tact withthe'end ofthe tubular Vstop member. lower and the flanged seatmg collar is similar to 42l 1I'.n"a"'fuel pump injector, in combination, a

, lpump block, a pump cylinder, a plunger in the cylinder, "port's" through locate, h'old and 'clampthe spray nozzle in tightly the pump block including a sleeved nut enveloping the cylinder and the spray nozzle, Saidspray nozzle having a seating in one end of the sleeved nut, the other end of the sleeved nut being screwed to the pump block, the outer diameter of the cylinder and the bore of the sleeved nutbeing such that an annular space constituting a fuel reservoir into which theports open is provided around the cylinder; sailreservoir being tightly sealed against leakage through the screw threaded connection between the pump block and the sleeved nut by means of al gasket ring squeezed tightly in contact with both the pump block and the sleeved nut by the wedge surface of a nut screwed on to the exterior of the sleeved nut.

3. In a fuel pump injector, in combination, a pump block, a pump cylinder integral with the pump block, a plunger in the cylinder, ports through the cylinder wall, controlled by the plunger, parts including a distance piece, an injection valve and a spray nozzle coaxial with the cylinder, there being a bore through the distance piece from the pump cylinder to the spray nozzle and the injection valve being a spring loaded disc valve in a pocket in the spray nozzle, said disc valve having a seating on the distance piece, and means to locate, hold and clamp the said parts together in; abutting and tightly assembled relationship to the pump block, comprising a sleeved nut enveloping the cylinder and the said parts; one of said parts having a seating in one end of the sleeved nut, the other end of the sleeved nut being screwed 4to the pump block, the outer diameter of the cylinder and the bore of the sleeved nut being such that an annular space constituting a fuel reservoir into which the ports open is provided around the cylinder.

4. In a fuel pump injector, in combination, a pump block, a pump vcylinder' integral with the pump block, a plunger in the cylinder, ports through 'the cylinder wall, controlled by the plunger, parts including a distance piece, an injection valve and a spray nozzle coaxial with the cylinder, and means to locate, hold and clamp the said parts together in .abutting and tightly assembled relationship to the pump block, comprising a sleeved nut enveloping the cylinder and the said parts, one of said parts having a seating in one end of the sleeved nut, the other end of the sleeved nut being screwed to the pump block, the outer diameter of the cylinder and vthe bore of the sleeved nut being such that an annular space constituting a fuel reservoir into which the ports open is provided around the cylinder.

CLYDE W. TRUXEIL, JR. 

